Top-Loading Straddle-Mounted Pipe Fusion Machine

ABSTRACT

A fusion machine which can be top-loaded on very large polyolefin pipes and pipelines has jaws which consist of an upper half jaw and lower left and right complemental jaws which pivot on the half jaw. Left and right actuators connected between the complemental jaws and the half jaw operate in one direction to cause the complemental jaws to rotate to an opened condition in which the upper half jaw can be lowered onto and lifted from the pipes to be fused and in the other direction to cause the complemental jaws to rotate to a closed condition in which the pipes to be fused are gripped so substantially around their circumferences as to resist their deformation from round during manipulation by the machine. The top-loading machine minimizes the need for heavy equipment to load and unload pipe to and from the fusion machine.

CROSS-REFERENCE TO PENDING APPLICATIONS

This application is a continuation application which claims priority topending U.S. patent application Ser. No. 15/005,554 filed Jan. 25, 2016,which is a continuation application that claims priority to U.S. patentapplication Ser. No. 14/029,652, filed Sep. 17, 2013, now U.S. Pat. No.9,242,410.

BACKGROUND OF INVENTION

This invention relates generally to fusion of polyolefin pipes and moreparticularly concerns the machines used to perform the pipe fusionprocess.

Fusion of small diameter pipe may usually be accomplished by hand-held,stand-mounted or cart-carried fusion devices. Little, if any, heavyequipment is necessary in the performance of the fusion process. Sticksof small diameter pipe are typically manually loaded through the top orend of the device for fusion. The fusion device can often be manuallydisconnected and removed from the pipeline or, at worst, the pipeline ismanually released and pulled from the device manually or using arelatively small motorized vehicle.

Fusion of large diameter pipe typically requires fusion machines mountedon wheeled carts or motorized vehicles and the pipe sticks and pipelinesare loaded and unloaded using various types of heavy equipment. A firstpipe stick is loaded onto the top of lower fixed half jaws and upperhalf jaws pivoted on the lower half jaws, usually manually, to clamp thefirst pipe stick to the fixed jaws. A second pipe stick is loaded ontothe top of lower sliding half jaws and upper half jaws are pivoted onthe lower jaws, usually manually, to clamp the second pipe stick to thesliding jaws. Once the fusion process is completed and the fixed andsliding jaws are opened, the fused pipeline is pulled to position thefree end of second stick in the fixed jaws and a third stick is loadedonto the sliding jaws for fusion into the pipeline. The equipment forloading the pipe sticks onto the sliding jaws and pulling the pipelinefrom the fixed jaws is likely very heavy and expensive and requiresadditional operators.

It is, therefore, an object of this invention to provide a pipe fusionmachine which reduces the need for use of additional heavy pipe-handlingequipment in performance of the pipe fusion process. And it is an objectof this invention to provide a pipe fusion machine which simplifies thepipe-handling steps of the pipe fusion process.

SUMMARY OF INVENTION

In accordance with the invention, a machine for fusing polyolefin pipeshas an upper half jaw, lower left and right complemental jaws, left andright pivots and at least one, and preferably left and right, actuators.The upper half jaw has an inside radius that is substantially equal tothe selected outside radius of the pipes being fused. The lower left andright complemental jaws each have an inside radius that is substantiallyequal to the inside radius of the upper half jaw. The left and rightpivots connect the lower left and right complemental jaws to theirrespective left and right portions of the half jaw. The left and rightactuators are connected between the lower left and right complementaljaws and their respective left and right portions of the half jaw.Operation of the actuators in one direction causes the lower left andright complemental jaws to rotate to an opened condition in which theupper half jaw can be lowered onto and lifted from the pipes to befused. Operation of the actuators in its other direction causes thelower left and right complemental jaws to rotate to a closed conditionin which the pipes to be fused are gripped so substantially around theircircumferences as to resist their deformation from round duringmanipulation by the machine and resist axial slippage during fusion.

The machine may also include at least one replacement set of lower leftand right complemental jaws. Each of the replacement sets isinterchangeable with the lower left and right complemental jaws and witheach other. Each replacement set has a different inside radius and theirinside radii are each different than the inside radius of the upper halfjaw. For each replacement set of complemental jaws, at least one insertis provided that can be mounted on the inside radius of the upper halfjaw. The inside radius of the insert or inserts associated with a set ofcomplemental jaws is substantially equal to the inside radius of thatset of complemental jaws. Thus, each replacement set of complementaljaws and its corresponding half jaw inserts enables use of the samemachine to handle pipes and/or pipelines of a different outside radius.

The free ends of the lower left and right complemental jaws and theirreplacement sets, if any, are tapered toward their respective insideradii to facilitate their closure beneath the pipe or pipeline lying onthe ground during pick-up.

Each actuator preferably includes a piston cylinder and a linkage thatare serially connected between the lower left and right complementaljaws and the left and right portions of the half jaw, respectively. Eachlinkage preferably includes a toggle and a link. The toggle is pivotedat a first axis on the upper half jaw. It is also pivotally connected ata second axis to a piston of its respective cylinder and at a third axisto one end of a link. The other end of the link is pivotally connectedat a fourth axis to a complemental jaw hub which is pivoted on the lowerportion of the upper half jaw. The complemental jaw is attached to andmoves in unison with the complemental jaw hub. The axes are parallel andthe linkage provides such a mechanical advantage between its respectivecylinder and complemental jaw as to assure that sufficient resistance todeviation of the pipeline or pipe stick from round during manipulationby the machine is maintained as long as the grip is closed on thepipeline or pipe stick and to resist axial slippage.

The machine preferably includes a gantry, a pair of spaced apart tracksand telescoping legs mounted at the front and rear of each track andsupporting the gantry above the tracks. A carriage mounted on the gantryhas spaced parallel guide rods. One upper half jaw is mounted forreciprocal sliding on the guide rods toward and away from another upperhalf jaw which is fixed on the guide rods. Another set of lower left andright complemental jaws, each having an inner radius substantially equalto the inner radius of said upper half jaw, is connected by another setof left and right pivots to their corresponding other left and rightportions of the other half jaw. Another actuator, and preferably anotherset of left and right actuators, are each connected between theircorresponding other lower left and right complemental jaws and left andright portions of the other half jaw, respectively. One direction ofoperation of the other left and right actuators causes the other lowerleft and right complemental jaws to simultaneously rotate to an openedcondition in which the other upper half jaw can be lowered onto andlifted from the pipes to be fused. The other direction of operation ofthe other left and right actuators causes the other lower left and rightcomplemental jaws to rotate to a closed condition in which the pipes tobe fused are gripped so substantially around their circumferences as toresist deformation thereof from round during manipulation by themachine.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention will become apparent uponreading the following detailed description and upon reference to thedrawings in which:

FIG. 1 is a front elevation view of a fusion machine according to theinvention;

FIG. 2 is a perspective view of the machine of FIG. 1;

FIG. 3 is a top plan view of the carriage of the machine of FIG. 1;

FIG. 4 is a perspective view of the machine of FIG. 1 gripping a pipestick/pipeline;

FIG. 5A is a front elevation view of a fully opened jaw of the machineof FIG. 1 positioned over a pipe/pipeline;

FIG. 5B is a front elevation view of the jaw of FIG. 5A lowered andpartially closed at ground level on the pipe/pipeline;

FIG. 5C is a front elevation view of the jaw of FIG. 5A fully closed onthe pipe/pipeline;

FIG. 6A is a perspective assembly view of a complemental jaw and acomplemental jaw adapter hub of the machine of FIG. 1;

FIG. 6B is a perspective view of the complemental jaw and complementaljaw adapter hub of FIG. 6A assembled;

FIG. 7A is a front elevation view of a fully opened jaw of the machineof FIG. 1 modified by replacement complemental jaws and half jaw insertsand positioned over a pipe/pipeline;

FIG. 7B is a front elevation view of the jaw of FIG. 7A lowered andpartially closed at ground level on the pipe/pipeline;

FIG. 7C is a front elevation view of the jaw of FIG. 7A fully closed onthe pipe/pipeline;

FIG. 8A is a front elevation assembly view of the jaw of FIG. 7A;

FIG. 8B is an enlarged front elevation view of the area BB of FIG. 8E;

FIG. 8C is an enlarged front elevation view of the area CC of FIG. 8E;

FIG. 8D is an enlarged perspective assembly view of the upper half jawand inserts of FIG. 8A;

FIG. 8E is a front elevation view of the jaw of FIG. 8A assembled;

FIG. 9A is a front elevation view illustrating the operation of thecylinders/pistons and linkages of the jaw of FIG. 7A to open the jaw;

FIG. 9B is a front elevation view illustrating the operation of thecylinders/pistons and linkages of the jaw of FIG. 7A to close the jaw;

FIG. 9C is a front elevation view illustrating the operation of thecylinders/pistons and linkages of the jaw of FIG. 7A to tightly grip thepipe/pipeline; and

FIG. 10 is a schematic diagram of the hydraulic system of the machine ofFIG. 1.

While the invention will be described in connection with a preferredembodiment thereof, it will be understood that it is not intended tolimit the invention to that embodiment or to the details of theconstruction or arrangement of parts illustrated in the accompanyingdrawings.

DETAILED DESCRIPTION The Machine

Looking first at FIGS. 1 and 2, a track-driven pipe fusion machine 10 isconfigured to be top-loaded onto a pipe stick S and onto a pipeline L towhich the stick is to be fused.

The machine 10 has a gantry 20 which is transported on a pair ofparallel tracks 21 to travel along the pipeline path terrain.Telescoping cylinder legs 23, 25, 27 and 29 connected to the gantry 20at each of its corners are operable to vary the gantry's elevation andlevel in relation to the terrain. A carriage assembly 30 including jaws60 for grabbing the pipeline L and pipe stick S during the fusionprocess is suspended from and changes elevation and level with thegantry 20.

The machine 10 performs the fusion process while stopped in a positionin which the tracks 21 straddle and the gantry 20 spans across thepipeline L and the pipe stick S. The jaws 60 are used to pick up,manipulate and release the pipeline L and a pipe stick S during thefusion process.

The jaws 60 are opened and closed in response to actuators 110 whichassure that sufficient resistance to deviation of the pipeline L and/orpipe stick S from round during manipulation by the machine 10 ismaintained as long as the grip is closed on the pipeline L and/or pipestick S and prevent axial slippage.

The machine 10 also includes an operator's platform 11 and controlcenter 13, a facer assembly 15 and a heater assembly 17 for performanceof the fusion process steps.

The Carriage Assembly

Turning to FIGS. 3 and 4, at least one fixed jaw 31 is mounted on therear end of the carriage assembly 30 for handling the pipeline L. Twosliding jaws 32 and 33 are mounted on the carriage assembly 30 forhandling the pipe stick S. A fourth jaw 34 can be selectively connectedfor operation either as a second fixed or as a third sliding jaw. Thecarriage assembly 30 as shown in an exemplary 2×2 configuration in whichthe first 31 and fourth 34 jaws are fixed and the second 32 and third 33jaws are sliding in unison. As best seen in FIG. 4, in thisconfiguration the fixed jaws 31 and 34 will usually be used to grip thepipeline L and the sliding jaws 32 and 33 will usually be used to gripthe pipe stick S. In a 3×1 configuration (not shown), the first jaw 31is fixed and the second, third and fourth jaws 32, 33 and 34 are slidingin unison. In the 3×1 configuration the single fixed jaw 31 will usuallybe used to grip the pipeline L and the three sliding jaws 32, 33 and 34will usually be used to grip the pipe stick S. This is especially usefulif the pipe stick S is to be connected to a T-junction in a pipeline, inwhich case the length of the T may be too short for a multiple jaw grip.The principles herein disclosed are applicable to both the 2×2 and the3×1 configurations of the carriage assembly 30.

In the 2×2 configuration shown, the carriage 30 has a guide rod supportplate 35 at its forward end and the outboard fixed jaw 31 at its aftend. Guide rods 37 extend in parallel and are fixed between the plate 35and the outboard fixed jaw 31. The support plate 35 has a centralaperture 39 for connection to a mounting link 41 on the forward end ofthe gantry 20. The fixed jaw 31 has lugs 43 symmetrically positioned andengagable on the aft end of the gantry 20. The sliding jaws 32 and 33are mounted on the forward portion of the guide rods 37 and are fixedagainst the opposite ends of the carriage cylinders 45 so that thesliding jaws 32 and 33 and the cylinders 45 move in unison on the guiderods 37. The fourth jaw 34 is mounted between the outboard fixed jaw 31and the inboard sliding jaw 32 but is fixed in relation to the outboardfixed jaw 31 by jaw conversion links 47. The piston rods 49 of thecarriage cylinders 45 extend through the inboard sliding jaw 32 and arefixed by rod extensions 51 to the first jaw 31. Thus, when the pistons49 are retracted in the cylinders 45, the sliding jaws 32 and 33 movetoward the fixed jaws 31 and 34 and, when the piston rods 49 areextended from the cylinders 45, the sliding jaws 32 and 33 move awayfrom the fixed jaws 31 and 34.

In the 3×1 configuration, the jaw conversion links 47 connect the fourthjaw 34 to the inboard sliding jaw 32 and the rod extensions 51 extendthrough the fourth jaw 34 and are fixed to the fixed jaw 31.

The Jaws

Turning to FIGS. 5A, 5B and 5C, each carriage assembly jaw 60, whetherfixed or sliding, includes an upper half jaw 61, lower left 63 and right65 complemental jaws and left 67 and right 69 pivots. In thisdisclosure, the upper half jaw 61 is so-called because, as shown, itsubstantially affords 180° of the grip. The lower jaws 63 and 65 asshown are quarter or 90° grips, but need not necessarily be quarter or90° jaws. They are referred to as complemental because, as shown, theysubstantially afford the remaining 180° to complete the circular grip.In the quarter jaw embodiment shown, the complemental jaws are symmetricwith respect to the center plane 73, but in non-quarter jaw embodimentsthe complemental jaws will not by symmetric. The upper half jaw 61 has agenerally trapezoidal outer perimeter 71 and is symmetric in relation toa vertical plane 73 through the center longitudinal axis 75 of thepipeline L and pipe stick S to be grasped. As best seen in FIG. 5C, ithas an inside radius 77 that is substantially equal to the selectedoutside radius of the pipeline L and pipe stick S being fused.

For the purposes of this description, assume that the pipeline L or pipestick S of FIGS. 5A, 5B and 5C have a two meter outside diameter and theupper half jaw 61, therefore, has a one meter inside radius. As bestseen in FIG. 5C, the complemental jaws 61 and 63 each have an insideradius 79 that is substantially equal to the inside radius of the upperhalf jaw 61, in this example also one meter.

As best seen in FIG. 5B, the outer perimeters of the complemental jaws63 and 65 are tapered toward their free ends to facilitate theirinsertion between the lower half of the pipe stick S or pipeline L andthe ground G to pick up the pipe stick S or pipeline L. As shown, thetapers increase incrementally toward the tips of the complemental jaws63 and 65 so as to converge toward their respective inside radii 79.

Continuing to look at FIGS. 5A, 5B and 5C, the complemental jaws 63 and65 have adapter hubs 81 at their upper ends. As best seen in FIGS. 6Aand 6B, the left hub 81 has a hook 83 on its inside portion and a clevis85 on its outside portion with lands 87 on the bottom of the clevis 85.The left complemental jaw 63 has a retaining pin 89 on its upper insideportion and a stop plate 91 on its upper outside portion. The leftcomplemental jaw 63 is attached to the left hub 81 by seating theretaining pin 89 in the hook 83 and securing the stop plate 91 inabutment with the lands 87 on the clevis 85 using screws 93 extendingthrough the stop plate 91 and into the clevis 85. The left hub 81 ispivoted for rotation on the lower portion of the left upper half jaw 61about a shaft 95 on the left upper half jaw 61 and the left complementaljaw 63 pivots in unison with the left hub 81 to which it is attached.The right hub 81 and complemental jaw pivot 69 configuration mirrors theleft hub 81 and complemental jaw pivot 69 configuration of FIGS. 6A and6B.

As seen in FIGS. 7A, 7B and 7C, the machine may also include at leastone replacement set 160 of lower left 163 and right 165 complementaljaws. Each replacement set 160 of complemental jaws 163 and 165 has adifferent inside radius 179 than the two meter diameter set 60 discussedabove and the other replacement sets 160. Assume that the pipeline L orpipe stick S of FIGS. 7A, 7B and 7C have a 54″ outside diameter and theupper half jaw 61, therefore, has a 27″ inside radius 77. As best seenin FIG. 7C, the lower left and right complemental jaws 163 and 165 eachhave an inside radius 179 that is substantially equal to the insideradius of the upper half jaw inserts 180, in this example also 27″. Forthis replacement set 160 of complemental jaws 163 and 165, at least one,and as shown two, inserts 180 are provided that are mountable on theinside radius 77 of the upper half jaw 61. The lower complemental jawFIGS. 6A and 6B for replacements 160 are installed as explained above inrelation to the complemental jaws 63 and 65 of the two meter outsidediameter pipeline L and pipe sticks S.

Installation of the inserts 180 for the upper half jaw 61 is illustratedin FIGS. 8A, 8B, 8C, 8D and 8E in relation to the 27″ outside radiuspipeline L and pipe sticks S. As seen in FIG. 8A, two inserts 180 areused to change the inside radius 77 of the upper half jaw 61. Looking atFIG. 8B, an L-shaped retainer 181 extends outward from the insert 180for engagement against a bar 183 on the half jaw 61. Turning to FIG. 8C,once the insert retainer 181 is engaged against the half jaw bar 183, alatch 185 on the insert 180 slides into and out of engagement with acatch 187 on the half jaw 61 to secure or release the insert 180 to orfrom the half jaw 61, respectively. As seen in FIG. 8E, the insideradius 189 of the inserts 180 associated with a set of complemental jaws160 is substantially equal to the inside radius 79 of that set ofcomplemental jaws 160. Thus, each set of corresponding complemental jaws160 and half jaw inserts 180 enables use of the same machine 10 tohandle pipe sticks S and pipelines L of a different outside radius.

In this exemplary application, the pipeline L or pipe sticks S of FIGS.7A, 7B and 7C have 54″ outside diameters. The upper half jaw 61 and itsassociated replacement lower complemental jaws 163 and 165 will,therefore, have one or more, and as shown, two inserts 180 defining a27″ inside radius.

As seen in FIGS. 7A, 7B and 7C, the free ends of the replacement sets160 of lower left and right complemental jaws 163 and 165 are, similarto the two meter diameter complemental jaws 63 and 65, tapered towardtheir respective inside radii 179 to facilitate their closure beneaththe pipe sticks S or pipeline L during pick-up.

The two meter (78.7″) and 54″ pipe diameters have been chosen for FIGS.5A-C and 7A-C, respectively, because it is presently anticipated thatthe same fusion machine 10 will be useful for fusing pipes of anydiameter within that range. However, fusion machines applying theprinciples herein taught can be made in many different sizes toaccommodate different ranges of pipe diameters.

The Actuators

Turning to FIGS. 9A, 9B and 9C, the left and right actuators 110 areconnected between the replacement lower left and right complemental jaws163 and 165 and their respective left and right portions of the half jaw61. As shown, the left and right actuators 110 are mirrored in relationto the plane 73. Each actuator 110 includes a cylinder 111 and piston113 and a linkage 120 serially connected between their respective lowerreplacement left and right complemental jaws 163 and 165 and left andright portions of the half jaw 61. Each linkage 120 preferably includesa toggle 121 and a link 123. The toggle 121 is pivoted at a first axis125 on the upper half jaw 61. It is also pivotally connected at a secondaxis 127 to the piston 113 of its respective cylinder 111 and at a thirdaxis 129 to one end of the link 123. The link 123 is also pivotallyconnected at a fourth axis 131 at its other end to the complemental jawadapter hub 81 which is pivotally mounted at a fifth axis 133 on thelower portion of the upper half jaw 61. The replacement complemental jaw163 or 165 is secured to and moves in unison with its respectivecomplemental jaw hub 81 as explained in relation to FIGS. 6A and 6B andthe complemental jaws 63 and 65. The axes 125, 127, 129, 131 and 133 areparallel.

When an actuator piston 113 is retracted into its cylinder 111, itstoggle 121 is pivoted on the first axis 125 toward the cylinder 111. Thetoggle 121 pulls the link 123 in tension, causing its complemental jawhub 81 to rotate about its pivot axis 97. The replacement complementaljaw 163 or 165 moves in unison with its hub 81, opening the complementaljaw 163 or 165. When an actuator piston 113 is extended from itscylinder 111, its toggle 121 is pivoted on the first axis 125 away fromthe cylinder 111. The toggle 125 pushes the link 123 in compression,causing its complemental jaw hub 81 to rotate about its pivot axis 133.The complemental jaw 163 or 165 moves in unison with its hub 81, closingthe complemental jaw 163 or 165. The linkage 120 provides such amechanical advantage between its respective cylinder 111 andcomplemental jaw 163 or 165 as to assure that sufficient resistance todeviation of the pipeline L and/or pipe stick S from round duringmanipulation by the machine 10 is maintained as long as the grip isclosed on the pipeline L and/or pipe stick S and that it resists axialslippage.

Hydraulic System

Turning to FIG. 10, the machine hydraulic system 140 includes an engine141, preferably an industrial liquid cooled diesel engine, closed looptrack drive pumps 143, an auxiliary open loop pump 145 and a hydraulicfluid reservoir 147. The system 140 powers right and left track motors149 to drive and steer the machine 10 from one fusion location toanother and into operating positions in which the machine 10 can pickup, manipulate and/or fuse pipeline L and pipe sticks S. The elevationand level of the gantry 20 is varied by simultaneous operation of thetwo front gantry telescoping cylinders 23 and 25 and independentoperation of the two rear gantry telescoping cylinders 27 and 29 toraise and lower the corners of the gantry 20 as necessary. The spacingof the fixed and sliding jaws 60 is controlled by operation of thecarriage cylinders 45 to reciprocate the sliding jaws on the guide rods37. The fusion machine jaws 60 are opened and closed by operation oftheir respective actuator cylinders 31 a and 31 b, 34 a and 34 b, 32 aand 32 b and 33 a and 33 c. As seen in FIGS. 9A, 9B and 9C, operation ofthe actuator cylinders 111 in one direction causes the lower left andright complemental jaws 63 and 65 or replacements 163 and 165 to rotateto an opened condition in which the upper half jaw 61 can be loweredonto and lifted from the pipe sticks S and/or pipeline L to be fused.Operation of the cylinders 111 in the opposite direction causes thelower left and right complemental jaws 63 and 65 or replacements 163 and165 to rotate to a closed condition in which the pipe sticks S and/orpipeline L to be fused are gripped so substantially around theircircumferences as to resist their deviation from round duringmanipulation by the machine 10 and to prevent slippage. The machine mayalso include a number of stripper cylinders 151 for use in removal ofthe heater during separation of the jaws after heating.

Operation

Assume for the exemplary application herein described that severalsticks S of pipe to be fused into a pipeline L are in end-to-endalignment with the pipeline L, that the jaws 60 of the fusion machine 10have been equipped with complemental jaws 63 and 65 or replacements 163and 165 and half jaw inserts 180 corresponding to the pipe outerdiameter and that the fourth jaw 34, if any, has been secured foroperation in the 2×2 configuration. Assume further that it is desirablethat the pipeline L be manipulated by the fixed jaws 31 and 34 and thepipe stick S be manipulated by the sliding jaws 32 and 33.

In performing the fusion process, the operator opens the complementaljaws 63 and 65 or replacements 163 and 165 to a fully openedconfiguration and adjusts the gantry 20 to a level suitable for the pipestick S to be received in the carriage assembly 30. The operator thendrives the machine 10 into a position in which the tracks 21 straddle,the gantry 20 spans across and the carriage assembly 30 is aligned withthe pipe stick S to be fused with the sliding jaws 32 and 33 proximatethe end of the pipe stick S to be fused.

In this position, the operator lowers the gantry 20 and begins closingthe sliding complemental jaws 63 and 65 or 163 and 165 as the tips dropbelow the midpoint of the pipe stick circumference. Lowering of thegantry 20 can, but need not necessarily, continue until the tips of thecomplemental jaw 63 and 65 or 163 and 165 contact the ground G. Closingof the complemental jaws 63 and 65 or 163 and 165 continues until theyare in the fully closed condition. At this point, the complemental jaws63 and 65 or 163 and 165 and half jaw 61, or half jaw inserts 180, ifnecessary, tightly grip the pipe stick S.

Once the pipe stick S is gripped, the gantry 20 can be raised, ifnecessary, to lift the gripped end of the pipe stick S above ground G.The operator can then drive the machine 10 and further change theelevation of the gantry 20 to a condition in which the gripped end ofthe pipe stick S is proximate, higher than and in longitudinal alignmentwith the end of the pipeline L to which the pipe stick S will be fusedand the fixed jaws 31 and 34 are aligned above the end of the pipeline Lto which the pipe stick S will be fused.

In this position, the operator again lowers the gantry 20 and beginsclosing the fixed complemental jaws 63 and 65 or 163 and 165 as the tipsof the fixed complemental jaws 63 and 65 or 163 and 165 drop below themidpoint of the pipeline circumference. Lowering of the gantry 20 can,but need not necessarily, continue until the tips of the complementaljaw 63 and 65 or 163 and 165 contact the ground G. Closing of thecomplemental jaws 63 and 65 or 163 and 165 continues until they are inthe fully closed condition. At this point, the complemental jaws 63 and65 or 163 and 165 and half jaw 61, or half jaw inserts 180, ifnecessary, tightly grip the pipeline L.

Once the pipeline L is gripped, the gantry 20 can be raised to lift thegripped ends of the pipe stick S and pipeline L above ground G to fusionlevel. With the center axes 75 of the pipeline L and pipe stick Slongitudinally aligned at fusion level, the operator adjusts the spacingbetween the fixed 32 and 33 and sliding jaws 32 and 33, if necessary,inserts the facer assembly 15 into a suitable facing position betweenthe fixed 31 and 34 and sliding jaws 32 and 33 and closes the spacing tobring the pipeline L and pipe stick S into abutment with opposite sidesof the facer.

After facing, the operator spreads the spacing between the fixed 31 and34 and sliding jaws 32 and 33, removes the facer assembly 15 from thespace, prepares a heater assembly 17 for insertion between the ends ofthe pipeline L and pipe stick S to be fused, adjusts the spacing ifnecessary to receive the heater assembly 17, inserts the heater assembly17 into a suitable heating position between the fixed 31 and 34 andsliding 32 and 33 jaws and closes the spacing to bring the pipeline Land pipe stick S into abutment with opposite sides of the heater.

After heating, the operator spreads the spacing between the fixed 31 and34 and sliding 32 and 33 jaws, removes the heater assembly 17 and closesthe spacing to bring the molten ends of the pipeline L and pipe stick Stogether. This condition is maintained under force until the joint hascooled sufficiently.

Once the joint has cooled, the operator lowers the gantry 20 and opensall of the jaws 60 simultaneously to release the fused pipeline L to theground G. This completes this exemplary fusion process for one pipestick S. The operator can then raise the gantry 20 sufficiently to allowthe machine 10 to be driven forward from the fused pipe stick S toanother pipe stick S for repetition of the process.

In some applications, rather than the exemplary process as abovedescribed, it may be desirable to use the fusion machine 10 to bring thepipe sticks S into their end-to-end alignment with the pipeline L at thebeginning of the process, and/or to secure the fourth jaw 34 to thesliding jaw 32 rather than to the fixed jaw 31 and/or to apply the fixedjaws 31 and 34 to the pipe stick S and sliding jaws 32 and 33 to thepipeline L.

The fusion process can be performed using known facer and heaterassemblies 15 and 17 and methods for control of the relative axialmovement of the sliding jaw or jaws with respect to the fixed jaws,examples of which are disclosed in U.S. Pat. Nos. 5,814,182, 6,021,832,6,212,747 and 6,212,748.

Thus, it is apparent that there has been provided, in accordance withthe invention, a straddle-mounted pipe fusion machine that fullysatisfies the objects, aims and advantages set forth above. While theinvention has been described in conjunction with specific embodimentsthereof, it is evident that many alternatives, modifications andvariations will be apparent to those skilled in the art and in light ofthe foregoing description. Accordingly, it is intended to embrace allsuch alternatives, modifications and variations as fall within thespirit of the appended claims.

What is claimed is:
 1. For fusing polyolefin pipes of selected outsideradius end-to-end, a machine comprising: an upper half jaw having aninner radius substantially equal to the selected outside radius of thepipes being fused; lower left and right complemental jaws each having aninner radius substantially equal to said inner radius of said upper halfjaw; and left and right pivots connecting said lower left and rightcomplemental jaws to left and right portions of said half jaw,respectively.
 2. A machine according to claim 1 further comprising atleast one actuator connected between said lower left and rightcomplemental jaws and said left and right portions of said half jaw, onedirection of operation of said at least one actuator causing said lowerleft and right complemental jaws to simultaneously rotate to an openedcondition in which said upper half jaw can be lowered onto and liftedfrom the pipes to be fused and another direction of operation of said atleast one actuator causing said lower left and right complemental jawsto rotate to a closed condition in which the pipes to be fused aregripped so substantially around their circumferences as to resistdeformation thereof from round during manipulation by the machine.
 3. Amachine according to claim 2, said at least one actuator comprising leftand right actuators connected between said lower left and rightcomplemental jaws and said left and right portions of said half jaw,respectively, one direction of operation of said actuators causing saidlower left and right complemental jaws to simultaneously rotate to anopened condition in which said upper half jaw can be lowered onto andlifted from the pipes to be fused and another direction of operation ofsaid actuators causing said lower left and right complemental jaws torotate to a closed condition in which the pipes to be fused are grippedso substantially around their circumferences as to resist deformationthereof from round during manipulation by the machine.
 4. A machineaccording to claim 3, each of said left and right actuators comprising acylinder and a linkage serially connected between said lower left andright complemental jaws and said left and right portions of said halfjaw, respectively.